A: Compelled is too light a word. My father calls this book my obsession and I have to admit, he’s right. In fact, I can pinpoint the precise moment it started. It was the first morning of my first trip to China: June 18, 1979. We were staying in the childhood home of my father, a doctor from Philadelphia who left Shanghai in 1949. Everything was going great until an uncle pulled my father aside and whispered, “Do you have any idea what happened to us?” Truth was, he had been clueless. Their lives had been destroyed, but we had no way of knowing it.

When we returned home to Philadelphia, my father didn’t dwell on the past. He moved on with his life. But I couldn’t let go. Maybe it was my nature as a reporter. I needed to unravel the history of my family.

Q: What did you find out?

A: I learned that during the Cultural Revolution from 1966 to 1976, no one in the family was spared. My grandmother was pressured to denounce her brother Watchman Nee, a religious leader who was sent to prison in 1956. My grandfather was accused of being an American spy (he wasn’t). My 16-year-old cousin was sent off to work in the countryside for seven years.

But the more I dug into the past, the more I realized that their problems started long before that. They started at the very beginning with the first convert more than a 150 years ago.

Q: Who was Watchman Nee?

A: Watchman Nee was one of the most influential Chinese Christians of the 20th century, along with Wang Mingdao and John Sung. In 1949, when China became a Communist nation, Watchman Nee had an estimated 70,000 followers, or more than 5 percent of the Protestant population at the time. He was never trusted by the Communist regime. They saw him as a political threat and he was charged as a counterrevolutionary.

Q: Why did the earlier Chinese Christians have problems?

A: When Protestant missionaries arrived in significant numbers in the 19th century, Christianity was seen as foreign. That alone caused trouble. China had an innate distrust of westerners. And not without cause. The Qing empire suffered military defeat at the hands of outsiders during the Opium Wars.

Over the next century, religion and politics often clashed. This happened in 1927 in Fuzhou, where my grandparents were living at the time. An anti-foreign, anti-Christian mob took to the streets and needed a scapegoat. My grandfather, the Rev. Lin Pu-chi, was an easy target. Western educated. Anglican. Dean of the cathedral. They subjected him to all kinds of physical abuse and taunts.

The amazing thing was that no one in the family knew this story. Not my father, not his siblings, no one. It vanished from the family narrative, probably because it was too sensitive to discuss.

Q: Why would Chinese people embrace the teaching of missionaries in the first place?

A: The first missionaries in Fuzhou had a hard time. Their message fell on hard ground in the city. But out in the countryside, it was a different story.

If you were a peasant, life was pretty much hand-to-mouth. Those early converts welcomed the message of “foreign ghosts,” who taught them that if you followed ten commandments from their holy book, you could find happiness now and forever.

I know from my aunt that the first convert in our branch of the Lin family was her great-grandfather, a fisherman-farmer who went to work for the missionaries as a cook.

Q: Did that missionary connection help the family?

A: Missionaries get criticized for trying to force their beliefs and culture on the Chinese people. But keep in mind that they also tried to improve lives. They opened schools and introduced western medicine through hospitals. Along the way, they drew followers.

Take a look at my family tree. Missionaries trained the cook’s son to be a doctor. They introduced him to his future bride, a teacher who had been born into a farm family and had gone to schools run by Irish and English women. The couple had a son, my grandfather. The missionaries sent him to the prestigious St. John’s University in Shanghai and then on to Philadelphia for seminary and graduate school at the University of Pennsylvania.

The family of my grandmother also went to mission schools.

So, you could say that if it wasn’t for the missionary contribution to education in 19th century China, I would not be here today to tell our story.

Q: How did you go about finding out about their lives?

A: I started by asking questions of my father and his siblings.

I never met my grandparents. They had died before our 1979 reunion in Shanghai. But luckily for me, my grandfather was a prolific writer. He left a long paper trail for me to follow, starting with the letters he wrote to us in English every month.

I also did a lot of hunting in archives. In Shanghai, I found a fiery sermon Rev. Lin delivered after the Japanese attacked the city in 1932. At Yale, I pored over articles he wrote as editor of the student newspaper at St. John’s University.

Q: What about in China? How did you research the book there?

A: I lived in Beijing with my husband and two children from 1996 to 1999 when I was the Asia correspondent for The Philadelphia Inquirer. On the side, I took many trips to sites from the family past, often with my cousin Terri Sun, who had emigrated to Australia but worked in China. We traveled all over.

We went to the Lin Ancestral Hall in the tiny bayside village of Erdu. I found genealogical records for our branch of the Lin family in a thick book called a jiapu. We also made a pilgrimage to the grave of our great-grandfather and toured the former Methodist girls’ school where our grandmother attended, the McTyeire School in Shanghai.

Q: Were there any surprises?

A: Many, but one I will never forget was a eureka! moment in the archives at Penn. My grandfather was born in 1894 and belonged to a generation of ambitious, educated men and women who wanted to make China more modern. In 1918, he sailed to America. In Philadelphia, he entered the Episcopal seminary and also enrolled at Penn, located on the west side of the Schuylkill River.

I went to Penn to look at his transcript. When the archivist handed me the document with his address and grades, I couldn’t believe it.

According to his records, my grandfather from Shanghai lived at 901 Clinton Street. My old address: 920 Clinton Street. We were neighbors, six decades apart.

Q: What’s happening now with Christianity in China?

A: China could have the largest Christian population in the world by 2025. That estimate comes from an expert on Christianity in China, sociologist Fenggang Yang of Purdue University. Religions of all stripes are experiencing a renaissance, not only Christianity. Why? It is the age-old search for meaning in our lives.

There is constant tension over religion. The government requires churches to register with the state, but many more opt not to. This causes problems.

But another thing to keep in mind is China is a vast country, so what is true in one place may not be true in another. In the summer of 2015, officials in the city of Wenzhou were tearing down crosses from churches. But just to the south, in the city of Fuzhou, where I was visiting, it was a different story. The Christians I met, even at house churches, did not feel the same threats.

Q: What has been your family’s reaction to the book?

A: For more than three decades I have been asking everyone questions. Lots and lots of questions. So it has not been easy for them and I am grateful for their patience. But it has been rewarding to find out things that no one knew, like the attack on my grandfather in 1927.

Some discoveries have been less traumatic. I unearthed a love story that my straight-laced, intellectual grandfather had published in English when he lived in Philadelphia in 1919. I found it in a magazine for overseas Chinese students. My father could not believe it.

Then, right before I sent my manuscript to the publisher, someone in Hong Kong sent me an article that Rev. Lin had written in 1932 about the need for a history of Protestant Christianity in China. He lamented that there were plenty of books by missionaries, but not enough from the Chinese perspective.